The Neutron star Interior Composition Explorer Mission


Current Activity:

Current time (UT): 2018-11-19 03:58:08
NICER most recent pointing: PSR_J0537-6910 From: 2018-11-19T03:50:20 until: 2018-11-19T04:04:25
Next pointing: PSR_J1838-0655 At: 2018-11-19T04:06:20 until: 2018-11-19T04:11:58


Requesting Targets of Opportunity (ToOs) with NICER

NICER is capable of following up on Targets of Opportunity (ToO) within 4 hours (depending on source visibility). TOO requests should be submitted via the ARK/RPS NICER Target of Opportunity/Director's Discretionary Time Request form.

The NICER team monitors the Gamma-ray Coordination Network (GCN)/Transient Astronomy Network (TAN).

Any questions regarding how to make TOO requests should be sent to the NICER Helpdesk via the HEASARC's Feedback Form.



NICER was launched aboard a SpaceX Falcon 9 rocket on June 3, 2017 at 17:07 EDT (21:07 UTC)

The Neutron star Interior Composition Explorer (NICER) is an International Space Station (ISS) payload devoted to the study of neutron stars through soft X-ray timing. Neutron stars are unique environments in which all four fundamental forces of nature are simultaneously important. They squeeze more than 1.4 solar masses into a city-size volume, giving rise to the highest stable densities known anywhere. The nature of matter under these conditions is a decades-old unsolved problem, one most directly addressed with measurements of the masses and, especially, radii of neutron stars to high precision (i.e., better than 10 percent uncertainty). With few such constraints forthcoming from observations, theory has advanced a host of models to describe the physics governing neutron star interiors; these models can be tested with astrophysical observations.

NICER will enable rotation-resolved spectroscopy of the thermal and non-thermal emissions of neutron stars in the soft (0.2-12 keV) X-ray band with unprecedented sensitivity, probing interior structure, the origins of dynamic phenomena, and the mechanisms that underlie the most powerful cosmic particle accelerators known. The NICER mission achieves these goals by deploying an X-ray timing and spectroscopy instrument on the International Space Station (ISS).

By answering a long-standing astrophysics question - How big is a neutron star? - NICER will confront nuclear physics theory with unique measurements, exploring the exotic states of matter within neutron stars through rotation-resolved X-ray spectroscopy. The capabilities that NICER brings to this investigation are unique: simultaneous fast timing and spectroscopy, with low background and high throughput. NICER will also provide continuity in X-ray-timing astrophysics more broadly, post-Rossi X-ray Timing Explorer, through a Guest Observer program. Finally, in addition to its science goals, NICER will enable the first space demonstration of pulsar-based navigation of spacecraft, through the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) enhancement to the mission, funded by the NASA Space Technology Mission Directorate's Game-Changing Development program.

NICER's X-ray Timing Instrument (XTI) represents an innovative configuration of high-heritage components. The heart of the instrument is an aligned collection of 56 X-ray "concentrator" optics (XRC) and silicon drift detector (SDD) pairs. Each XRC collects X-rays over a large geometric area from a roughly 30 arcmin2 region of the sky and focuses them onto a small SDD. The SDD detects individual photons, recording their energies with good (few percent) spectral resolution and their detection times to an unprecedented 100 nanoseconds RMS relative to Universal Time. Together, this assemblage provides a high signal-to-noise-ratio photon-counting capability within the 0.2-12 keV X-ray band, perfectly matched to the typical spectra of neutron stars as well as a broad collection of other astrophysical sources.

From NICER's ISS platform, a star-tracker-based pointing system allows the XTI to point to and track celestial targets over nearly a full hemisphere. The pointing system design accommodates the ISS vibration and contamination environments, and enables (together with NICER's GPS-based absolute timing) high-precision pulsar light-curve measurements through ultra-deep exposures spanning the 18-month mission lifetime.

Simulated NICER count rates and spectra can be derived using the WebPIMMS and WebSPEC tools. The Viewing tool can be used to determine the times when a specific sky position is potentially visible to NICER.

More details are availbale in NICER's Mission Guide. A 12-slide overview of NICER science is available here.

More NICER documentation and publications.

If you would like to receive email about NICER developments, please subscribe to the NICER-announce email list.

For those interested in general astronomy/astrophysics information please go to the Education and Public Outreach site.

Artist concept of NICER

Latest News
  • NICERDAS Version 5 released (24 Oct 2018)
    The NICER data reduction software Version 5 was released on Oct 23 2018 with the release of HEASoft 6.25 . NICERDAS 5.0 includes updates to most tasks and includes new task, nicertimeconv, to do basic time conversions.
  • IGR J17591-2342 second re-brightening observed with NICER (21 Sep 2018)
    NICER observations of the second re-brightening of the accreting millisecond pulsar IGR J17591-2342 show it reaching its highest flux yet seen, with strong pulsations remaining after almost 60 days post-outburst.
  • NICER Guest Observer Program approved by NASA (07 Sep 2018)
    NASA has approved a Guest Observer program for NICER. We expect that the Announcement of Opportunity will be released this fall, with proposals due by the end of the calendar year. More information will be posted on the NICER home page when available.
  • NICER and NuSTAR Identification of X-ray Transient IGR J17591-2342 (17 Aug 2018)
    Observations by NICER and NuSTAR of the X-ray transient IGR J17591-2342 discovered by INTEGRAL on August 12 show that the new transient is an accreting millisecond pulsar in outburst. The pulsar has a spin frequency of approximately 527 Hz and an orbital period of 0.37 days.
  • A Rapidly Spinning Black Hole with a Warped Disk (17 Jul 2018)
    NICER provides a detailed look at a rapidly-spinning black hole feeding off its companion star.

[More NICER News]